1)
(2x - 9)(x + 6) - x(x + 6) = 0
(x+6)(2x-9-x)=0
(x+6)(x-9)=0
x+6=0 x-9=0
x= - 6 x=9
2)
(8x+ 4)(x - 10) + (10 - x)(x - 8) = 0
(8x+ 4)(x - 10) - (x - 10)(x - 8) = 0
(x-10)(8x+4-x+8)=0
(x-10)(7x+12)=0
x-10=0 7x+12=0
x=10 7x= - 12 /:7
x= - 12/7
Нажми на скрин там понятро
4x^2 - 8x <= 5
4x^2 - 8x - 5 <= 0
4x^2 - 8x - 5 = 0
D = 64+80=144 = 12^2
x1 = (8+12)/8 = 2,5
x2 = (8-12)/8 = -1/2
2x^2 + x + x + 1 >= 3
2x^2 + 2x - 2 >= 0
x^2 + x - 1 >= 0
D = 1 + 4 = 5
x1 = (-1 + sqrt5)/2
x2 = (-1 - sqrt5)/2